(a) Field of the Invention
Embodiments of the present invention relate generally to flat panel displays. More specifically, embodiments of the present invention relate to a display device including a photo sensor and a driving method therefor.
(b) Description of the Related Art
Various kinds of flat panel displays have been developed for various uses. Particularly, display devices having a touch sensing function or an image sensing function have been developed.
In general, touch-sensitive displays often employ a touch screen panel capable of sensing a contact, where this panel is attached to the display device. However, such configurations often suffer from high cost, yield reduction due to addition of an adhesion process, luminance deterioration of the display panel, and the like. Accordingly, a technology for embedding a sensor into the display area of the display device has been developed. The embedded sensor often employs a thin film transistor or capacitor, outputs a sensing signal according to change in irradiated light due to an external contact and the like, and determines contact information such as a contact position of an object, intensity of contact, and the like by using the sensing signal.
One such sensor is a photo sensor, i.e. a sensor sensing change in light, which may generate a sensing signal by using photocurrent generated by incident light and may acquire contact information by using the sensing signal. The light sensed by the sensor may be lights having various frequencies such as infrared light, visible light, and the like, and a light source generating the light sensed by the sensor may be positioned in the display device. For example, a backlight, which is an internal light source for displaying an image of the display device, may be configured so as to emit light having a wavelength suitable for the photo sensor in addition to visible light. However, the photo sensor may be influenced by light from an additional exterior light source and as a result, inexact contact information may be acquired.
Furthermore, photo sensors typically employ a photosensitive transistor. This transistor is a three-terminal element that determines whether or not contact exists via a photocurrent formed by irradiating light upon the channel part of the transistor. However, even when no light shines upon the photo sensor, photo leakage current may be present and, as a result, an error in the contact information may occur.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.